According to the PMBOK® Guide (Project Management Body of Knowledge), specifically within the Project Integration Management knowledge area and the Develop Project Charter process:

Project Charter (Option C): This is the document issued by the project initiator or sponsor that formally authorizes the existence of a project and provides the project manager with the authority to apply organizational resources to project activities. Per PMI standards, a standard Project Charter includes high-level information such as the project purpose or justification, measurable project objectives, success criteria, a summary milestone schedule, and a summary budget. It also identifies the high-level risks and the assigned project manager.

Work Breakdown Structure (WBS) (Option A): This is a hierarchical decomposition of the total scope of work. It focuses on deliverables and work packages, not on project justification, budgets, or milestone schedules.

Requirements Document (Option B): This document describes how individual requirements meet the business need for the project. While it includes measurable criteria for the product, it does not contain the project ' s financial authorization or the milestone schedule.

Project Management Plan (Option D): This is a comprehensive document that describes how the project will be executed, monitored, and controlled. While it incorporates high-level information from the charter, the charter is the specific, formal starting document where these summary-level components are first established and authorized.

In the PMI framework, the Project Charter serves as a bridge between the organization ' s strategic objectives and the project ' s tactical execution. By documenting the summary budget and milestone schedule at this early stage, the sponsor set the boundaries within which the Project Manager must plan the detailed project activities.